Method of making a commutator



May.: 17, 1966 L. REISNECKER METHOD OF MAKING A COMMUTATOR Filed Feb.12, 1962 United States Patent 3,251,120 METHOD OF MAKING A COMMUTATORLudwig Reisnecker, Stuttgart-Rotating, Germany, assignor to Robert BoschG.m.b.H., Stuttgart, Germany Filed Feb. 12, 1962, Ser. N 172,435

' 5 Claims. (Cl; 29-155.54)

' commutator.

One of the objects of the present invention is to provide a commutatormanufacturing process which is exceedingly simple and exceedinglyinexpensive, as compared to known commutator manufacturing processes.

Another object of the present invention is to provide a process of theabove type according to whichthe raw material from which the commutatoris made is exceedingly inexpensive.

It is also an object of the present invention to provide a commutator ofthe above type which has portions to which armature leads may be veryconveniently connected.

Also, it is an object of the present invention to provide a process inwhich a minimum amount of finishing is required during the last stagesof the process.

With the above objects in view the invention includes, in a process formanufacturing a commutator in part from an electrically conductive bandhaving an inner face which in the finished commutator is directed towardthe commutator axis and an outer face which in the finished commutatoris directed away from this axis and having a flange extending along aside edge of the band and projecting only from the outer face thereof,the steps of pressing two series of tranverse grooves into this band,one series from the inner toward the outer face thereof so as to defineelongated segments connected to each other only by bridging portionslocated at the outer face of the band. and at the bases of the grooves,respectively, and the other series of grooves being respectively alignedwith the first series of grooves and extending into the above-mentionedflange up to the outer face of the band, so that each segment issubstantially L-shaped and has a relatively long leg extendingtransversely across the band and a relatively short" leg extendingsubstantially perpendicularly with respect to the band. A plurality ofthese L-shaped segments, which are still connected by the above bridgingportions, are rolled into the shape of a cylinder with the relativelyshort legs of the-segments directed away from the cylinder axis, andthen all of the segments are embedded in a cylindrical bodyofelectrieally non-conductive material which fills the above-mentionedfirst series of grooves and which is surrounded by the cylindrical rowof segments. Then the above-mentioned bridging portions are removed soas to leavethe segments separated from each other and supported only bythe electrically non-conductive material, and the above-mentionedrelatively short legs of the sements are adapted to have armature leadsconnected thereto.

The novel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, willbe best understood from the following description of specificembodiments when read in connection with the accompanying drawings, inwhich:

FIG. 1 is a fragmentary perspective illustration of an electricallyconductive band used for making the segments of the commutator of theinvention, this band being shown in FIG. 1 partially in theconfiguration it segments, while they are still connected to each other,

are rolled into the shape of a cylinder; and

FIG. 4 is a partly sectional, perspective illustration of the finishedcommutator of the invention.

Referring to FIGS. 1 and 2, there is shown therein an elongated band 10of an electrically conductive material such as copper. The upper face ofthe band 10, as viewed in FIG. 1, forms the inner face which is directedtoward the axis of the commutator when the latter is finished, and thelower face of the band 10, as viewed in FIG. 1, forms the outer facethereof which is directed away from the axis of the finished commutator.As is apparent from FIGS. 1 and 2, the band 10 is, in accordance withthe invention, pressed with suitable dies so as to have formed thereintwo series of transverse grooves. The one series of grooves extendsfromthe inner (upper as viewed in FIG. 1) face of the band 10 to theouter face thereof so as toseparate the band into elongated segmentswhich are connected to each other by the bridging portions 11 located atthe outer face of the band 10 at the bases of the first series ofgrooves, respectively, and the second series of grooves is formed in aflange of the band 10, this second series of grooves being respectivelyaligned with the first series of grooves and cooperating therewith toprovide each segment with a relatively long leg 10" and a relativelyshort leg 10', the relatively long leg extending across the band 10 andthe relatively short leg extending substantially perpendicularly withrespect to the band. This band 10 is of L-shaped cross-section before itis acted upon so as to be formed with the structure shown in FIGS. 1 and2, so that the original band 10 has along one side edge a flange whichextends only from the outer face of the band, which is the lower facethereof as viewed in FIG. 1. The grooves which extend into this flangealso extend up to the outer face of the band 10, as is apparent fromFIG. 2, so that in this way these pressing operations serve to form thetwo series of grooves which define the L-shaped segments 10', 10" whichare interconnected at this time only by the bridging portions 11 ofthe'band. The two series of grooves may be formed simultaneously in theband by pressing on the latter with suitable dies which simultaneouslyact from both sides of the band to give it the configuration indicatedin FIGS. 1 and 2.

Curved holding claws 12 are raised from those faces of the segmentswhich are directed away from the relatively short legs 10' thereof,these curved holding claws being formed by any suitable cutting toolswhich cut into the several segments longitudinally of their relativelylong legs 10' so as to raise from each segment a pair of curved holdingclaws 12, as indicated in FIG. 1.

With the band 10 treated as described above and as shown in FIGS. 1 and2, the operator selects a number of segments 10, 10 equal to the desirednumber of segments in the finished commutator, and this number ofsegments is separated from the band and is rolled into the cylindricalshape shown in FIG. 3, and it will be noted that when the series ofsegments are rolled into this shape the relatively short legs 10'thereof are directed away from the cylinder axis, and of course theholding claws 12 are directed toward the cylinder axis. It should benoted that before the selected number of segments are rolled into thecylindrical shape shown in FIG. 3, a part of each bridging portion 11extending from the left edge Patented May 17, 1966 commutator to theshaft of the armature.

the regions thereof which include the relatively short legs and FIG. 3clearly shows only the remaining portions of the bridging portions 11interconnecting the several segments at their relatively long'legs 10'.

The assembly of FIG. 3 is then embedded, in a known way and in asuitable mold, in a body 13 (FIG. 4) of electrically non-conductivematerial, and it will be noted that the holding claws 12 serve to anchorthe segments in the body of material 13, this body of electricallynonconductive material filling the spaces between the segments, thesespaces being formed by the above-mentioned grooves. The remainingbridging portions 11 are then machined away from the segments in asuitable machine tool or the like so that in this way the remainder ofeach bridging portion 11 is removed and the segments are now entirelyunconnected from each other and are supported only by the body 13 ofelectrically non-conductive material. The cylindrical body 13 surroundsand engages an inner steel tube 14 which facilitates connection of theThe individual shorter legs 10' of the several commutator segments,after the commutator is finished, are formed with slots, by suitablesaws, for example, and these slots are adapted to each receive two ormore wires of the armature winding, these armature leads being soldered,for example, to the several commutator segments.

Thus, with the process of the invention there is provided a commutatorwhich during its manufacture includes a series of segments connected toeach other and rolled into the shape of a cylinder, and the segments ofthe commutator of the invention each has a substantially L-shapedconfiguration formed, in accordance with the present invention, from thecross-sectional configuration of the original band 10' which is workedupon according to the invention. This particular configuration makes itvery convenient to provide in the shorter leg 10' of each segment a slotadapted to receive the leads of the armature. Up to the present time thecommutator segments were formed from fiat, unprofiled bands. Byproviding the commutator of the invention from a band 10 which is ofL-shaped cross-section, the leg 10 provides additional area, as comparedto conventional commutator segments, capable of being used in thosemachines where more than two armature leads are required to be connectedto each segment.

Of course, it is within the scope of the invention to provide a band 10which in its original configuration is substantially U-shaped so as tohave a pair of flanges respectively extending from the opposite sideedges of the band, since such a construction is particularly suited forrelatively small commutators which when provided with a pair of suchflanges are far more capable of withstanding the stresses resulting fromthe pressing operations, and in the case of such small commutators whenthe bridging portions 11 are machined away the additional flange is alsomachined away, this latter additional flange being provided only inorder to provide such a relatively small commutator with sufficientstrength to withstand the forces to which it is subject during themanufacture of the commutator.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofcommutators differing from the types described above.

While the invention has been illustrated and described as embodied incommutators and processes for manufacturing commutators, it is notintended to be limited to the details shown, since various modificationsand structural changes may be made without departing in any way from thespirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can by applying current knowledgereadily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this inventionand, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. In a process for manufacturing a commutator in part from anelectrically conductive band having an inner face which in the finishedcommutator is directed toward the commutator axis and an outer facewhich in the finished commutator is directed away from said axis andhaving a flange extending along a side edge of the band and projectingonly from said outer face thereof, the steps of pressing two series oftransverse grooves from opposite sides into said band, one series fromsaid inner toward said outer face thereof to define elongated segmentsconnected to each other by bridging portions located at the outer faceof the band and at the bases of the grooves, respectively, and the otherseries being respectively aligned with said first series of grooves andextending into said flange up to said outer face of said band, so thateachsegment is substantially L-shaped and has a relatively long legextending across the band and a relatively short leg extendingsubstantially perpendicularly to the band; rolling a plurality of theL-shaped segments, connected by said bridging portions, into the shapeof a cylinder with said relatively short legs directed away from thecylinder axis; embedding said segments in a cylindrical body ofnon-conductive material which fills said first, series of grooves andwhich is surrounded by the cylindrical roll of segments; and removingsaid bridging portions so as to other and connected together only bysaid non-conductive material, said shorter legs of said segments beingadapted to have armature leads connected thereto.

2. In a process for manufacturing a commutator in part from anelectrically conductive band having an inner face which in the finishedcommutator is directed toward the commutator axis and an outer facewhich in the finished commutator is directed away from said axis andhaving a flange extending along a side edge of the band and projectingonly from said outer face thereof, the steps of pressing two series oftransverse grooves from opposite sides into said band, one series fromsaid inner toward said outer face thereof to define elongated segmentsconnected to each other by bridging portions located at the outer faceof the band and at the bases of the grooves, respectively, and the otherseries being respectively aligned with said first series of grooves andextending into saidflange up to said outer face of said band, so thateach segment is substantially L=shaped and has a relatively long legextending across the band and a relatively short leg extendingsubstantially perpendicularly to the band; removing from the band a partof each bridging portion extending from said side edge of the bandinwardly beyond'said relatively short legs of said segments, so that thesegments are separated from each other in the region of said relativelyshort legs thereof; rolling a plurality of L-shaped segment-s, connectedby said bridging portion, into the shape of a cylinder with saidrelatively short legs directed away from the cylinder axis; embeddingsaid segments in a cylindrical body of elec trically non-conductivematerial which fills said first series of grooves and which issurrounded by the cylindrical roll of segments; and removing theremainder of said bridging portions so as to leave said segmentsseparated from each other and supported only by said non-conductivematerial, said relatively short legs of said segments being adapted tohave armature leads connected thereto.

3. In a process for'manufacturing a'commutator in part from anelectrically conductive band having an inner face which in the finishedcommutator is directed toward leave said segments separated from eachthe commutator axis and an outer face which in the finished commutatoris directed away from said axis and having a flange extending along aside edge of the band and projecting only from said outer face thereof,the steps of pressing two series of transverse grooves from oppositesides into said band, one series from said inner toward said outer facethereof to define elongated segments connected to each other by bridgingportions located at the outer face of the band and at the bases of thegrooves, respectively, and the other series being respectively alignedwith said first series of grooves and extending into said flange up tosaid outer face of said band, so that each segment is substantiallyL-shaped and has a relatively long leg extending across the band and arelatively short leg extending substantially perpendicularly to theband; raising a holding claw from that face of each segment which isdirected away from said relatively short leg thereof; rolling aplurality of the L-shaped segments, connected by said bridging portions,into the shape of a cylinder with said relatively short legs'of saidsegments directed away from the cylinder axis; embedding said segmentsand said holding claws thereof in a cylindrical body of electricallynon-conductive material which fills said first series of grooves andwhich is surrounded by the cylindrical row of segments; and removingsaid bridging portions so as to leave said segments separated from eachother and supported only by said electrically non-conductive material,said relatively short legs of said segments being adapted to havearmature leads connected thereto.

4. In a process for manufacturing a commutator in part from anelectrically conductive band having an inner face which in the finishedcommutator is directed toward the commutator axis and an outer facewhich in the finished commutator is directed away from said axis andhaving a flange extending along a side edge of the band and projectingonly from said outer face thereof, the steps of simultaneously pressingtwo series of transverse grooves from opposite sides into said band, oneseries from said inner toward said outer face thereof to defineelongated segments connected to each other by bridging portions locatedat the outer face of the band and at the bases of the groove-s,respectively, and the other series being respectively aligned with saidfirst series of grooves and extending into said flange up to said outerface of said band, so that each segment is substantially L-shaped andhas a relatively long leg extending across the band and a relativelyshort leg extending substantially perpendicularly to the band; removingfrom the band a part of each bridging portion which extends from saidside edge of the band inwardly beyond said relatively short legs of saidsegments; raisin-g from each of said segments, at a face thereof whichis directed away from said relatively short leg thereof, a curvedholding claw; rolling a plurality of the L-shaped segments, connected bythe remainder of said bridging portions, into the shape of a cylinderwith said relatively short legs directed away from the cylinder axis;embedding said segments in a cylindrical body of electricallynon-conductive material which fills said first series of grooves andwhich receives said holding claws, said cylindrical body of electricallynon-conductive material being surrounded by the cylindrical row ofsegments; and removing the remainder of said bridging portions so as toleave said L-shaped segments separated from each other and connectedtogether only by said electrically non-conductive material, saidrelatively short legs of said segments being adapted to have armatureleads connected thereto.

5. In a process for manufacturing a commutator, the steps of firstforming a band of L-shaped cross section from electrically conductivematerial, said band having an inner face which in the finishedcommutator is directed toward the commutator axis and an outer facewhich in the finished commutator is directed away from said axis andhaving a flange extending along one side edge of the band and projectingonly from said outer face thereof; simultaneously pressing two series oftransverse grooves from opposite sides into said band of L-sha-ped crosssection, one series from said inner toward said outer face thereof todefine elongated segments connected to each other by bridging portionslocated at the outer face of the band and at the bases of the grooves,respectively, and the other series being respectively aligned with saidfirst series of grooves and extending into said flange up to said outerface of said band, so that each segment is substantially L-shaped andhas a relatively long leg extending across the band and a relativelyshort leg substantially perpendicular of the band; rolling a pluralityof the L- shaped segments, connected by said bridging portions, into theshape of a cylinder with said relatively short legs directed away fromthe cylinder axis; embedding said segments in a cylindrical body ofnon-conductive material which fills said first series of grooves andwhich is surrounded by the cylindrical roll of segments; and removingsaid bridging portions so as to leave said segments separated from eachother and connected together only by said non-conductive material, saidshorter legs of said segments being adapted to have armature leadsconnected thereto.

References Cited by the Examiner UNITED STATES PATENTS 2,634,495 4/1953Callsen et al 29 1 55.54 2,953,698 9/1960 Gianotto 310 23.5

FOREIGN PATENTS 816,033 7/1959 Great Britain.

JOHN F. CAMPBELL, Primary Examiner.

MILTON O. HIRSHFIELD, WHITMORE A. WILTZ,

R. W. CHURCH, Assistant Examiners.

1. IN A PROCESS FOR MANUFACTURING A COMMUTATOR IN PART FROM ANELECTRICALLY CONDUCTIVE BAND HAVING AN INNER FACE WHICH IN THE FINISHEDCOMMUTATOR IS DIRECTED TOWARD THE COMMUTATOR AXIS AND AN OUTER FACEWHICH IN THE FINISHED COMMUTATOR IS DIRECTED AWAY FROM SAID AXIS ANDHAVING A FLANGE EXTENDING ALONG A SIDE EDGE OF THE BAND AND PROJECTINGONLY FROM SAID OUTER FACE THEREOF, THE STEPS OF PRESSING TWO SERIES OFTRANSVERSE GROOVE FROM OPPOSITE SIDES INTO SAID BAND, ONE SERIES FROMSAID INNER TOWARD SAID OUTER FACE THEREOF TO DEFINE ELONGATED SEGMENTCONNECTED TO EACH OTHER BY BRIDGING PORTIONS LOCATED AT THE OUTER FACEOF THE BAND AND AT THE BASES OF THE GROOVES, RESPECTIVELY, AND THE OTHERSERIES BEING RESPECTIVELY ALIGNED WITH SAID FIRST SERIES OF GROOVES ANDEXTENDING INTO SAID FLANGE UP TO SAID OUTER FACE OF SAID BAND, SO THATEACH SEGMENT IS SUBSTANTIALLY L-SHAPED AND HAS A RELATIVELY LONG LEGEXTENDING SUBSTANTIALLY PERPENDICULARLY RELATIVELY SHORT LEG EXTENDINGSUBSTANTIALLY PERPENDICULARLY TO THE BAND; ROLLING A PLURALITY OF THEL-SHAPED SEGMENTS, CONNECTED BY SAID BRIDGING PORTIONS, INTO THE SHAPEOF A CYLINDER WITH SID RELATIVELY SHORT LEGS DIRECTED AWAY FROM THECYLINDER AXIS; EMBEDDING SAID SEGMENTS IN A CYLINDRICALY BODY OFNON-CONDUCTIVE MATERIAL WHICH FILLS SAID FIRST SERIES OF GROOVES ANDWHICH IS SURROUNDED BY THE CYLINDRICAL ROLL OF SEGMENTS; AND REMOVINGSAID BRIDGING PROTIONS SO AS TO LEAVE SAID SEGMENTS SEPARATED FROM EACHOTHER AND CONNECTED TOGETHER ONLY BY SAID NON-CONDUCTIVE MATERIAL, SAIDSHORTER LEGS OF SAID SEGMENTS BEING ADAPTED TO HAVE ARMATURE LEADSCONNECTED THERETO.